Imaging element, imaging apparatus, its control method, and control program

ABSTRACT

An imaging element having a layered structure including a first chip having a pixel portion in which pixels for photoelectrically converting an optical image of an object and generating a pixel signal are arranged two-dimensionally and a second chip in which a drive means of the pixel portion is arranged, and having a first output path to output the pixel signals of at least a first pixel group in the pixel portion and a second output path to output the pixel signals of a second pixel group, comprises the a conversion means for converting the pixel signals of the first and second output paths into digital signals and a control information generation means for generating control information of a photographing operation of the object by using the digital signal converted by the conversion means, wherein at least a part of the conversion means is arranged in the first chip.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging element having a layeredstructure and an imaging apparatus having the imaging element and, moreparticularly, to an imaging element having such a construction that anevaluation value for photometry, distance measurement, and the like aredetected in accordance with image data.

2. Description of the Related Art

In the related arts, when obtaining position information of an objectwhich is used in focus control in an imaging apparatus, the positioninformation is obtained on the basis of an image signal which is outputfrom an imaging element. There is also used a method whereby an opticalsignal from an object is directly input to a dedicated detectingapparatus and position information is obtained on the basis of a phasedifference in an image shown by the optical signal. In the case ofobtaining position information on the basis of image data, since thededicated detecting apparatus is unnecessary, the imaging apparatus canbe miniaturized.

FIG. 16 is a diagram for describing timing for the autofocus imagepickup operation (AF evaluation image pickup) at the time of a live viewin the imaging apparatus in the related arts. As illustrated in thediagram, in the imaging apparatus in the related arts, image pickuptiming is specified by a vertical sync signal (Vertical Driving Pulse:VD). When an AF control signal is turned on, an image for AF evaluationis picked up in response to the VD after a live view image pickupperiod. When the AF control signal is turned off, the apparatus entersthe live view image pickup period again.

As mentioned above, since the live view image pickup period forobtaining the image for live view and the AF operation period forobtaining the image for AF evaluation are serially arranged along a timebase, the image for live view and the image for AF evaluation are notsimultaneously picked up. Therefore, as illustrated in the diagram,since the image for AF evaluation is picked up for the AF operationperiod locating between the image pickup periods (frames) of the imagefor live view, a time lag exists between the image for live view and theimage for AF evaluation.

In addition, although the live view display is performed even when theimage for AF evaluation is picked up, at this time, the live viewdisplay is performed on the basis of the image for AF evaluation. Asillustrated in FIG. 7, when the image for AF evaluation is picked up,since a frame rate is set to be higher than the live view image pickupperiod, a thinning-out rate in the read-out of the imaging element ishigh and a deterioration in image quality cannot be avoided.

In order to avoid such a drawback, for example, there is a constructionin which a pixel for focus signal detection is provided in a pixelportion of the imaging element separately from a pixel for an imagepickup signal. According to such a construction, the apparatus has notonly a read-out mode for live view in which the signal for image pickupfor a live view display is read out but also a read-out mode for focusdetection and autoexposure (AE) in which the signal for focus detectionand the signal for image pickup to be used for photometry informationfor autoexposure are read out of the imaging element. Such read-outmodes are circulatively and repetitively performed every frame (refer toJapanese Patent Application Laid-Open No. 2009-89105).

However, in Japanese Patent Application Laid-Open No. 2009-89105, sincethe image signal (that is, charges) is read out from the imaging elementon a pixel unit basis, not only it takes a time to transfer the chargesbut also a transfer data amount increases, thereby increasing electricpower consumption. Further, since the image signal serving as an outputof the imaging element is processed by another control apparatus or thelike, if the transfer data amount is large, a processing burden in thecontrol apparatus increases. In addition, in Japanese Patent ApplicationLaid-Open No. 2009-89105, since the pixel for focus signal detection isprovided in the pixel portion, an area of the pixel for the image pickupsignal is eventually reduced and the pixel for focus signal detection isnot used when obtaining the image pickup signal (image signal), so thatthe image quality deteriorates.

SUMMARY OF THE INVENTION

It is, therefore, an aspect of the invention to provide an imagingelement in which a data transfer time is shortened and image qualitydoes not deteriorate.

To accomplish the above aspect, according to the invention, an imagingelement having a layered structure which includes a first chip having apixel portion in which pixels each for photoelectrically converting anoptical image of an object and generating a pixel signal are arranged ina matrix form and a second chip in which a drive unit of the pixelportion is arranged and having a first output path for outputting thepixel signals of at least a first pixel group in the pixel portion and asecond output path for outputting the pixel signals of a second pixelgroup, comprising: a conversion unit configured to convert the pixelsignals of the first output path and the second output path into digitalsignals; and a control information generation unit configured togenerate control information of a photographing operation of the objectby using the digital signal converted by the conversion unit, wherein atleast a part of the conversion unit is arranged in the first chip.

According to another aspect of the invention, there is also provided animaging apparatus comprising: a photographing optical system for formingan optical image of an object; the foregoing imaging element for pickingup the optical image; a control unit configured to control driving ofthe imaging element in accordance with an image pickup mode of theimaging apparatus; and a display unit configured to display an image onthe basis of the digital signal of the first output path of the imagingelement driven by the control unit.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate exemplary embodiments, features,and aspects of the invention and, together with the description, serveto explain the principles of the invention.

FIG. 1 is a block diagram illustrating a construction of an imagingapparatus using an imaging element according to the first embodiment ofthe invention.

FIGS. 2A and 2B are diagrams for describing a construction of theimaging element according to the first embodiment of the invention.

FIG. 3 is a diagram for describing a pixel selection in a first chip ofthe imaging element according to the first embodiment of the invention.

FIG. 4 is a diagram illustrating image pickup timing in an AF evaluationmode of the imaging apparatus in the first embodiment of the invention.

FIG. 5 is a diagram illustrating a flowchart for the control operationof the imaging apparatus in the first embodiment of the invention.

FIG. 6 is a block diagram illustrating a construction of an imagingelement according to the second embodiment of the invention.

FIG. 7 is a diagram illustrating image pickup timing in a photometryevaluation mode of an imaging apparatus in the second embodiment of theinvention.

FIGS. 8A and 8B are diagrams illustrating an example of a constructionof a layered chip of an imaging element according to the thirdembodiment of the invention.

FIG. 9 is a block diagram illustrating a construction of the imagingelement according to the third embodiment of the invention.

FIG. 10 is a diagram illustrating an example of a setting of ADconversion conditions when selecting rows for live view and whenselecting rows for AF in the imaging element according to the thirdembodiment of the invention.

FIGS. 11A and 11B are diagrams illustrating input/output characteristicsof an AD conversion when selecting rows for live view and when selectingrows for AF in the imaging element according to the third embodiment ofthe invention.

FIG. 12 is a block diagram illustrating a construction of a column ADconverter of an imaging element according to the fourth embodiment ofthe invention.

FIG. 13 is a diagram illustrating timing for the operation of a columnAD conversion of an imaging element according to the fourth embodimentof the invention.

FIG. 14 is a block diagram illustrating a construction of the imagingelement according to the fourth embodiment of the invention.

FIG. 15 is a block diagram illustrating a construction of an imagingelement according to the fifth embodiment of the invention.

FIG. 16 is a diagram illustrating timing for the autofocus image pickupoperation in the live view operation in an imaging apparatus in therelated arts.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

Various exemplary embodiments, features, and aspects of the presentinvention will be described in detail below with reference to thedrawings.

First Embodiment

FIG. 1 is a block diagram illustrating a construction of an imagingapparatus having an imaging element according to the first embodiment ofthe invention. The illustrated imaging apparatus is applied to, forexample, a digital still camera with a moving image function or a videocamera.

In the diagram, an imaging apparatus 100 has an optical barrel 101, animaging element 102, a drive unit 103, a signal processing unit 104, acompression expansion unit 105, a control unit 106, a light emittingunit 107, an operation unit 108, an image display unit 109, and an imagerecording unit 110.

The optical barrel 101 has a lens unit (not shown; hereinbelow, simplycalled a lens) serving as a photographing optical system and an opticalmechanism unit 111. The lens converges (that is, focuses) light (opticalimage) from an object onto the imaging element 102. Although not shown,the optical mechanism unit 111 has an AF mechanism, a zoom drivingmechanism, a mechanical shutter mechanism, an iris mechanism, and thelike. The optical mechanism unit 111 is driven by the drive unit 103under control by the control unit 106.

The imaging element 102 according to the present embodiment has a pixelportion 201, which will be described hereinafter, and an A/D converter(not shown) and is a CMOS type image sensor of what is called an XYread-out type. The imaging element 102 executes the image pickupoperation such as exposure, signal read-out, reset, and the like by thedrive unit 103 which operates under control by the control unit 106, andoutputs an image pickup signal (also referred to as an image signal). AnAF evaluation value detection unit 112 is provided for the imagingelement 102. On the basis of contrast information and phase differenceinformation which are obtained from the image signal obtained by theimaging element 102, the AF evaluation value detection unit 112 detectsan AF evaluation value (autofocus evaluation value) at timing which iscontrolled by the control unit 106. The AF evaluation value detectionunit 112 outputs the AF evaluation value to the control unit 106.

The signal processing unit 104 executes signal processings such as whitebalance adjustment processing, color correction processing, AE (AutoExposure) processing, and the like to the image signal which is anoutput of the imaging element 102, under control by the control unit 106and outputs as image data. The compression expansion unit 105 operatesunder control by the control unit 106. The compression expansion unit105 executes a compression coding processing to the image data which isan output of the signal processing unit 104, by a predetermined stillimage data format such as a JPEG (Joint Photographic Coding ExpertsGroup) method or the like. The compression expansion unit 105 executesan expansion decoding processing to the coded image data transmittedfrom the control unit 106. The compression expansion unit 105 mayexecute the compression coding/expansion decoding processing to movingimage data by an MPEG (Moving Picture Experts Group) method or the like.

The control unit 106 is, for example, a micro controller having a CPU(Central Processing Unit), a ROM (Read Only Memory), a RAM (RandomAccess Memory), and the like. The CPU integratedly controls the wholeimaging apparatus 100 by executing a program stored in the ROM.

If it is determined that an exposure value of the object is small by theAE processing by the signal processing unit 104, the light emitting unit107 irradiates light to the object to illuminate the object. As a lightemitting unit 107, for example, a strobe apparatus using a xenon tube oran LED light emitting apparatus is used.

The operation unit 108 has, for example, various kinds of operation keyssuch as a shutter release button and the like, a lever, and a dial andtransmits an operation signal corresponding to the input operation ofthe user to the control unit 106.

The image display unit 109 has, for example, a display device such as anLCD (Liquid Crystal Display) or the like and an interface circuit forthe LCD and displays an image shown by the image data transmitted fromthe control unit 106 to the display device. The image recording unit 110is, for example, a recording medium such as portable semiconductormemory, optical disk, HDD (Hard Disk Drive), magnetic tape, or the likeand stores the image data, as an image file, which is compression-codedby the compression expansion unit 105. The image recording unit 110reads out the image file designated by the control unit 106 and outputsto the control unit 106.

The fundamental operation of the imaging apparatus 100 illustrated inFIG. 1 will now be described. The imaging apparatus in the presentembodiment has a still image photographing mode and a moving imagephotographing mode as photographing modes which can be set by theoperation of the operation unit 108 and has a function for reproducingand displaying the images which are photographed and recorded in thosephotographing modes.

For example, when a still image is photographed, in the imaging element102 prior to the image pickup, a CDS processing and an AGC processingare sequentially executed to the image signal which is output from apixel 201 and, thereafter, the obtained signal is converted into adigital image signal by an A/D converter. The digital image signal isoutput to the AF evaluation value detection unit 112 and the signalprocessing unit 104.

On the basis of contrast information obtained from the digital imagesignal, the AF evaluation value detection unit 112 calculates an AFevaluation value (control information) and outputs the AF evaluationvalue to the control unit 106. The control unit 106 decides a controlamount of the optical mechanism unit 111 on the basis of the AFevaluation value and controls the drive unit 103 in accordance with thecontrol amount. Thus, the optical mechanism unit 111 is driven by thedrive unit 103.

The signal processing unit 104 executes, for example, an image qualitycorrection processing to the digital image signal, generates a camerathrough image signal, and transmits the camera through image signal tothe image display unit 109 through the control unit 106. Thus, the imagedisplay unit 109 displays the camera through image expressed by thecamera through image signal. The user can perform an image angleadjustment while observing the camera through image.

When a shutter release button of the operation unit 108 is depressed inthis state, the image pickup signal (digital image signal) of one frameis sent to the signal processing unit 104 from the imaging element 102by the control of the control unit 106. The signal processing unit 104executes the image quality correction processing to the digital imagesignal of one frame and transmits the digital image signal (image data)obtained after the processing to the compression expansion unit 105. Thecompression expansion unit 105 compression-codes the image data andtransmits the coded image data to the image recording unit 110 throughthe control unit 106. Thus, an image file corresponding to the picked-upstill image is recorded in the image recording unit 110.

When the image file recorded in the image recording unit 110 isreproduced, the control unit 106 reads out the selected image file fromthe image recording unit 110 in accordance with an operation input fromthe operation unit 108. The control unit 106 sends the read-out imagefile to the compression expansion unit 105 and allows the compressionexpansion unit 105 to execute the expansion decoding processing. Thedecoded image data is sent to the image display unit 109 through thecontrol unit 106. Thus, a still image corresponding to the image data isreproduced and displayed on the image display unit 109.

When moving image data is recorded, the digital image signal which isoutput from the imaging element 102 is input to the signal processingunit 104 by the control of the control unit 106. The image data which issequentially processed in the signal processing unit 104 iscompression-coded by the compression expansion unit 105. The codedmoving image data is sequentially transferred from the compressionexpansion unit 105 to the image recording unit 110 and is recorded as amoving image file.

When the moving image file recorded in the image recording unit 110 isreproduced, the control unit 106 reads out the selected moving imagefile from the image recording unit 110 in accordance with an operationinput from the operation unit 108. The control unit 106 sends theread-out moving image file to the compression expansion unit 105 andallows the compression expansion unit 105 to execute the expansiondecoding processing. The decoded moving image data is sent to the imagedisplay unit 109 through the control unit 106. Thus, a moving imagecorresponding to the moving image data is reproduced and displayed onthe image display unit 109.

As will be obviously understood from the above description, in theexample illustrated in FIG. 1, the control unit 106 and the drive unit103 function as a control unit and a read-out control unit. The controlunit 106 and the image display unit 109 function as a display controlunit.

FIGS. 2A and 2B are diagrams for describing a construction of theimaging element 102 according to the present embodiment. FIG. 2A is aperspective view of the imaging element in the present embodiment. FIG.2B is a block diagram illustrating the construction of the imagingelement.

In FIG. 2A, the imaging element 102 has a first chip 20 and a secondchip 21 and the first chip 20 is layered on the second chip 21. Thefirst chip 20 has the plurality of pixels 201 arranged in a matrix form.The first chip 20 is layered in such a manner that a pixel array faces alight incident side (that is, it is located on a light receiving side ofan optical image). Pixel drive circuits such as column scanning circuits213-a and 213-b, row scanning circuit 212, and the like are formed onthe second chip 21, and the foregoing AF evaluation value detection unit112 is also formed.

As mentioned above, if the pixels 201 are formed on the first chip 20and the pixel drive circuits and the AF evaluation value detection unit112 are formed on the second chip 21, a manufacturing process ofperipheral circuits of the imaging element 102 and the pixel portion canbe separated. Thus, narrowing of a wire width in the peripheralcircuits, a high operation speed caused by highly-increasing a wiredensity, reducing a device size, and a high functionality can beplanned.

As illustrated in FIG. 2B, on the first chip 20, the pixels 201 arearranged in a matrix form and each pixel 201 is connected to a transfersignal line 203, a reset signal line 204, and a row selection signalline 205 in the horizontal direction (row direction). Each pixel 201 isalso connected to column signal lines 202-a and 202-b in the verticaldirection (column direction). Each of the column signal lines 202-a and202-b connects the pixels to different read-out destinations on a rowunit basis.

As illustrated in the diagrams, each of the pixels 201 has a photo diodePD serving as a photoelectric conversion element, a transfer transistorM1, a reset transistor M2, an amplifying transistor M3, a selectingtransistor M4, and a floating diffusion FD. In the example illustratedin the diagrams, each of the transistors is an n-channel MOSFET (MOSField-Effect Transistor).

The transfer signal line 203, reset signal line 204, and row selectionsignal line 205 are connected to gates of the transfer transistor M1,reset transistor M2, and selecting transistor M4, respectively. Thosesignal lines 203 to 205 extend in the horizontal direction tosimultaneously drive the pixels on the same row. Consequently, a rollingshutter of a line-sequential operation type or a global shutter of awhole-line simultaneous operation type can be controlled. Further, thecolumn signal line 202-a or 202-b is connected to a source of theselecting transistor M4 on a row unit basis.

The photo diode PD accumulates the charges generated by thephotoelectric conversion. A P-side of the photo diode PD is connected toa ground and an N-side is connected to a source of the transfertransistor M1. When the transfer transistor M1 is turned on, the chargesin the photo diode PD are transferred to the FD. Since a parasiticcapacitance exists in the FD, the charges transferred to the FD areaccumulated.

A power source voltage Vdd is applied to a drain of the amplifyingtransistor M3 and its gate is connected to the FD. The amplifyingtransistor M3 amplifies the charges (that is, voltage) of the FD toconvert into a voltage signal. The selecting transistor M4 selects thesignal reading-out pixels on a row unit basis by the row selectionsignal line 205. A drain of the selecting transistor M4 is connected toa source of the amplifying transistor M3. The source of the selectingtransistor M4 is connected to the column signal lines 202.

When the selecting transistor M4 is turned on by the row selectionsignal line 205, a voltage signal corresponding to the voltage of the FDis output to the column signal lines 202. The power source voltage Vddis applied to a drain of the reset transistor M2 and its source isconnected to the FD. When the reset transistor M2 is turned on by thereset signal line 204, the voltage of the FD is reset to the powersource voltage Vdd.

A column ADC block 211 is arranged on the second chip 21 every columnarrangement of the pixels 201 and the column ADC 211 is connected to thecolumn signal line 202-a or 202-b. Further, the row scanning circuit212, the column scanning circuits 213-a and 213-b, a timing controlcircuit 214, horizontal signal lines 215-a and 215-b, a change-overswitch 216, a frame memory 217, and the AF evaluation value detectionunit 112 are disposed on the second chip 21.

The timing control circuit 214 controls operation timing of the rowscanning circuit 212, column scanning circuits 213-a and 213-b, columnADC block 211, and switch 216 under control of the control unit 106. Therow scanning circuit 212 scans each row. Each of the column scanningcircuits 213-a and 213-b scans each column. The horizontal signal lines215-a and 215-b transfer output signals (image signals) of the columnADC blocks 211 at timing which are controlled by the column scanningcircuits 213-a and 213-b.

The frame memory 217 temporarily stores the image signal which is outputfrom the horizontal signal line 215-b. The AF evaluation value detectionunit 112 detects an AF evaluation value in accordance with the imagesignal stored in the frame memory 217 and sends the AF evaluation valueto the control unit 106. The change-over switch 216 is a switch forselectively outputting the image signal which is output to thehorizontal signal line 215-b to one of the AF evaluation value detectionunit 112 and the signal processing unit 104. The image signaltransferred to the horizontal signal line 215-a is sent to the signalprocessing unit 104.

FIG. 3 is a diagram for describing a selection construction to read outthe pixels to the column signal line 202-a or 202-b in the first chip 20illustrated in FIGS. 2A and 2B. In FIG. 3, for example, it is assumedthat the pixel portion of (6 rows×8 columns) is illustrated and therespective pixels are arranged according to the Bayer array.

When the apparatus enters a focus control mode by the operation of theoperation unit 108 illustrated in FIG. 1, the control unit 106 separatesthe reading-out rows of the imaging element 102 so that the image pickupfor live view and the image pickup for detection of the AF evaluationvalue can be simultaneously performed. That is, the change-over switch216 is switched so that the horizontal signal line 215-b is connected tothe frame memory 217. Thus, the image signal for live view is output tothe column signal line 202-a and the image signal for detection of theAF evaluation value is output to the column signal line 202-b.

In FIG. 3, row numbers 1 and 2 indicate rows to pick up the image fordetection of the AF evaluation value and row numbers 3 to 8 indicaterows to pick up the image for live view. In the example illustrated inthe diagram, the read-out scan is sequentially performed on a row unitbasis and the read-out scan is repetitively performed on a 8-row unitbasis.

In the image pickup for detection of the AF evaluation value, threepixels are read out among four pixels of a same color in the verticaldirection in a thinning-out manner to attach importance to a frame rate.On the other hand, in the image pickup for live view, one pixel isthinned out among four pixels of a same color in the vertical directionand three pixels are added to attach importance to image quality. Inother words, in the pickup of the image for detection of the AFevaluation value, a first pixel group is read out at a first frame rate.In the pickup of the image for live view, a second pixel group is readout at a second frame rate slower than the first frame rate.

By separately performing the image pickup for AF scanning and the imagepickup for live view every selected rows as mentioned above, the imagesignals of the frame rates of different data sizes can be obtained fordifferent charge accumulation times.

Voltage signals (analog signals) which are output from the column signallines 202-a and 202-b are converted from the analog signals into digitalsignals (image signals) by the column ADC blocks 211 illustrated inFIGS. 2A and 2B. The image signals as outputs of the column ADC blocks211 are read out from the column ADC blocks 211 to the horizontal signalline 215-a or 215-b by the column scanning circuit 213-a or 213-b. Theimage signals which are read out to the horizontal signal line 215-a aresent to the signal processing unit 104. The image signals which are readout to the horizontal signal line 215-b are output to the switch 216 andare output to the signal processing unit 104 or the frame memory 217under control by the control unit 106. The switching operation by thechange-over switch 216 is performed on a frame unit basis.

In the AF evaluation mode (that is, autofocus control mode), the imagesignals are recorded from the horizontal signal line 215-b into theframe memory 217 through the change-over switch 216. At this time, theAF evaluation value detection unit 112 detects the AF evaluation valueon the basis of contrast information in the image signals recorded inthe frame memory 217. The AF evaluation value is sent from the AFevaluation value detection unit 112 to the control unit 106.

In the following description, at the time of image pickup, an outputpath established by the column signal line 202-a and the horizontalsignal line 215-a is called “channel Ch1” and an output path establishedby the column signal line 202-b and the horizontal signal line 215-b iscalled “channel Ch2”.

FIG. 4 is a diagram illustrating image pickup timing in the AFevaluation mode in the camera 100 illustrated in FIG. 1.

As illustrated in the diagram, image pickup timing is specified by thevertical driving pulse (VD). If the AF evaluation mode is set, thecontrol unit 106 raises the AF control signal (to the H level) inresponse to a trailing edge of the vertical driving pulse VD at time T0.Subsequently, when the vertical driving pulse VD rises, the control unit106 simultaneously starts the live view image pickup using the channelCh1 and the image pickup for AF evaluation using the channel Ch2synchronously with the vertical driving pulse VD.

For a period of time of T0˜TF1, the image signals for AF evaluationwhich are read out of the pixel portion 201 through the channel Ch2 arestored into the frame memory 217 through the horizontal signal line215-b and the change-over switch 216. For a period of time of TF1˜TF2,the AF evaluation value detection unit 112 calculates an AF evaluationvalue by using the image signals for AF stored in the frame memory 217.After that, for a period of time of TF2˜TF3, the AF evaluation valuedetection unit 112 outputs the AF evaluation value to the control unit106.

The control unit 106 compares the AF evaluation value with apredetermined AF expected value. When the AF evaluation value satisfiesa predetermined condition with the AF expected value, the control unit106 lowers the AF control signal (time T1). When the AF control signaltrails, only the image pickup for AF evaluation is stopped and the liveview image pickup is continuously performed.

In the example illustrated in the diagram, for the period of time of theone vertical driving pulse VD, the image for live view is picked up byone frame and the images for AF evaluation (AF scan) are picked up bythree frames. When the control unit 106 sets the AF control signal tothe L level (time T1), the AF evaluation is finished.

In the imaging apparatus having the imaging element according to thepresent embodiment mentioned above, in the AF evaluation mode, there isno need to send the image data to the control unit 106 through thesignal processing unit 104 and obtain the AF evaluation value. That is,since the AF evaluation value of a small data capacity is directlyoutput from the imaging element 102 to the control unit 106, theelectric power can be reduced due to a decrease in processing burden.

FIG. 5 is a diagram illustrating a flowchart for the live view controloperation in the photographing operation of the imaging apparatus 100 inthe present embodiment. The control operation according to the flowchartillustrated in the diagram is realized by a method whereby the controlunit 106 executes a program to control each unit.

When a power supply of the camera 100 is turned on and the camera entersa standby state, that is, a photographing preparation state before imagepickup, the control unit 106 discriminates whether or not the camera isin the AF evaluation mode (step S502). That is, the control unit 106discriminates whether or not the AF evaluation mode is set. If the AFevaluation mode is not set (NO in step S502), the control unit 106starts the live view image pickup (step S503) and advances to step S515,which will be described hereinafter. If the AF evaluation mode is set(YES in step S502), the control unit 106 turns on the AF control signal(H level) (step S504). Subsequently, the control unit 106 substitutes“0” into a variable “n” adapted to count the number of times of AFevaluation image pickup, thereby initializing (step S505).

Subsequently, as described in FIG. 4, the control unit 106 starts thepickup of the images for AF evaluation (step S506) and starts the pickupof the images for live view in step S516. After the image pickup for AFevaluation is started, the control unit 106 increases the variable n by“1” (step S507). After that, the AF evaluation value detection unit 112detects an AF evaluation value AF_K in response to the image signal forAF evaluation obtained according to the image pickup for AF evaluationunder control by the control unit 106 (step S508).

Subsequently, the control unit 106 discriminates whether or not the AFevaluation value AF_K satisfies the following expression (1), that is, apredetermined evaluation condition with respect to K_min and K_max as AFexpected values (step S509).

K_min<AF_K<K_max  (1)

The AF expected values K_min and K_max indicate a minimum value and amaximum value of the AF evaluation value which is expected and arepreliminarily recorded into the control unit 106 at the time of a designof the camera 100 or an adjustment of the camera 100.

When the AF evaluation value AF_K does not satisfy the expression (1)(NO in step S509), the control unit 106 obtains a feedback controlamount on the basis of the AF evaluation value AF_K. The control unit106 drives the drive unit 103 in accordance with the feedback controlamount and drives a focus lens provided for the optical mechanism unit111 along the optical axis (step S510).

Subsequently, the control unit 106 discriminates whether or not thevariable (the number of times of AF evaluation image pickup) n is equalto a predetermined number (in this instance, 3) (step S511). If thenumber of times of AF evaluation image pickup is less than 3 (NO in stepS511), the control unit 106 is returned to the processing of step S506and performs the image pickup for AF evaluation. On the other hand, ifthe number of times of AF evaluation image pickup is equal to 3 (YES instep S511), the control unit 106 performs the live view display (stepS512), thereafter, is returned to the processing of step S505, and setsthe number n of times of AF evaluation image pickup to zero.

If the AF evaluation value AF_K satisfies the expression (1) (YES instep S509), the control unit 106 turns off the AF control signal (to theL level) (step S513), and stops the image pickup for AF evaluation inthe imaging element 102 (step S514). The control unit 106 displays theimage corresponding to the image signal for live view which is picked upto the image display unit 109 (step S515) and enters a standby state.

In the flowchart illustrated in FIG. 5, the control unit 106 stops theimage pickup for AF evaluation and, thereafter, displays the imagecorresponding to the image signal obtained by the pickup of the imagefor live view of step S516. When the image pickup for live view of stepS503 is started, the control unit 106 advances to the processing of stepS515 and performs the live view display.

In the first embodiment of the invention, since the image for live viewand the image for AF evaluation are simultaneously picked up asmentioned above, a time lag caused at the time of performing the AFevaluation can be shortened. At the time of the AF evaluation, sinceonly the AF evaluation value of the small data capacity is directly sentfrom the imaging element 102 to the control unit 106, a signal outputburden is reduced and the electric power consumption can be decreased.

Although the example in which the AF is performed at the time of liveview has been described above in the present embodiment, the abovemethod can be also used to another moving image photographing withoutlimiting to live view. In this instance, the AF evaluation value isdirectly output from the imaging element 102 to the control unit 106 andthe control unit 106 controls the optical mechanism unit 111 by thedrive unit 103 in accordance with the AF evaluation value. However, thedrive unit 103 may drive the optical mechanism unit 111 in accordancewith the AF evaluation value.

As mentioned above, according to the first embodiment of the invention,separately from the image pickup for live view, the image signal of ahigh frame rate is generated and, at the same time, the imaging elementdetects the AF evaluation value in accordance with the image signal.Therefore, a data transfer time is shortened and the image quality inthe live view does not deteriorate. Consequently, the electric powerconsumption can be also suppressed.

Second Embodiment

Subsequently, an imaging apparatus having an imaging element accordingto the second embodiment of the invention will be described. Since aconstruction of the imaging apparatus according to the second embodimentis similar to that of the camera illustrated in FIG. 1, its descriptionis omitted here. A construction of the imaging element 102 differs fromthat in the first embodiment (FIG. 2B). The present embodiment will bedescribed hereinbelow with respect to an example of a still imagephotographing at the time of the photometry operation with a lightemitting unit such as a strobe apparatus.

FIG. 6 is a block diagram illustrating the construction of the imagingelement according to the present embodiment. In FIG. 6, substantiallythe same component elements as those in the imaging element illustratedin FIGS. 2A and 2B are designated by the same reference numerals andtheir description is omitted here.

In the imaging element 102 illustrated in FIG. 6, the second chip 21 hasa photometry value evaluation unit 601 in place of the AF evaluationvalue detection unit 112. The photometry value evaluation unit 601 isconnected to the frame memory 217 and is connected to the control unit106. In the first chip 20, the photometry value evaluation unit 601calculates a color ratio and an exposure value as photometry values onthe basis of the image signals which are read out through the columnsignal line 202-b and the horizontal signal line 215-b (that is, channelCh2). The photometry value evaluation unit 601 outputs photometrycontrol data such as white balance coefficient, light emitting controlamount of the light emitting unit 107, and the like to the control unit106 on the basis of the photometry value. The control unit 106 sends acontrol command to the signal processing unit 104 and the light emittingunit 107 in accordance with the photometry control data and controls awhite balance correction in the signal processing unit 104 and a lightemitting amount of the light emitting unit 107.

FIG. 7 is a diagram illustrating image pickup timing in a photometryevaluation mode in the second embodiment.

When the photometry evaluation mode is set, the control unit 106simultaneously starts the pickup of the image for live view using thechannel Ch1 and the pickup of the image for photometry evaluation usingthe channel Ch2 synchronously with the vertical driving pulse VD inresponse to a trailing edge of the vertical driving pulse VD at timeT70. In the pickup of the image for photometry evaluation, the pickup ofthe image for photometry evaluation for the white balance coefficientand the light emitting control of the light emitting unit 107 isperformed. In this instance, the pickup of the image for photometryevaluation to calculate the white balance coefficient is called “imagepickup for white balance coefficient calculation” and the pickup of theimage for photometry evaluation to control the light emission is called“image pickup for light emitting control amount photometry”.

First, for a period of time of T70˜T71, the image pickup for whitebalance coefficient calculation is performed. At this time, the imagesignal for white balance coefficient evaluation which is read out of thepixel portion 201 through the channel Ch2 is stored into the framememory 217 through the horizontal signal line 215-b and the change-overswitch 216. For a period of time of T71˜T72, the photometry valueevaluation unit 601 calculates the white balance coefficient by usingthe image signal for white balance coefficient evaluation stored in theframe memory 217. After that, for a period of time of T72˜T73, thephotometry value evaluation unit 601 outputs the white balancecoefficient to the control unit 106. The white balance coefficient whichis output is used for correction of the white balance of the imagesignal in the signal processing unit 104.

Subsequently, at time T73, the control unit 106 raises the lightemitting control signal (to the H level) and starts the image pickup forlight emitting control amount photometry. At time T74, the control unit106 lowers the light emitting control signal (to the L level) and stopsthe image pickup for light emitting control amount photometry. Thus, fora period of time of T73˜T74, the image pickup for light emitting controlamount photometry of the light emitting unit 107 at the time ofphotographing a still image is performed and the image signal for lightemitting control amount evaluation is stored in the light emitting unit107. For the period of time of T73˜T74, since the light emitting controlsignal is turned on, a previous light emission (that is, pre-emitting oflight) by the light emitting unit 107 is performed, and the image pickupfor light emitting control amount photometry as an image pickup tocalculate an exposure amount of the object is performed.

For a period of time of T74˜T75, the photometry value evaluation unit601 calculates an exposure value regarding the object by using the imagesignal for light emitting control amount evaluation stored in the framememory 217 and generates a light emitting control amount on the basis ofthe exposure value. Subsequently, for a period of time of T75˜T76, thephotometry value evaluation unit 601 outputs the light emitting controlamount to the light emitting control amount control unit 106.

At time T76, the control unit 106 switches the photometry evaluationmode to the still image photographing mode and turns on the lightemitting control signal, thereby allowing the light emitting unit 107 toemit light (main emitting of light). At this time, the control unit 106controls the light emitting amount of the light emitting unit 107 inaccordance with the light emitting control amount. Further, the controlunit 106 switches the change-over switch 216, outputs the image signalwhich is output through the channel Ch2 to the signal processing unit104, and transfers the image signals which are read out of all pixels inthe pixel portion 201 to the signal processing unit 104.

In the example illustrated in the diagram, the images for live view ofone frame are picked up for the period of time of the one verticaldriving pulse VD, and for this period, the image pickup for calculationof the white balance coefficient, the calculation and output of thewhite balance coefficient, the image pickup for light emitting controlamount photometry, and the calculation and output of the light emittingcontrol amount are performed.

In the present embodiment, since the image for live view and the imagefor photometry evaluation are simultaneously picked up as mentionedabove, a time lag caused at the time of performing the photometryevaluation can be shortened. At the time of the photometry evaluation,only the photometry evaluation value (the white balance coefficient andthe light emitting control amount) of the small data capacity isdirectly sent from the imaging element 102 to the control unit 106, thesignal output burden is reduced and the electric power consumption canbe decreased.

In the present embodiment, the photometry evaluation value is directlysent from the imaging element 102 to the control unit 106 and thecontrol unit 106 controls the signal processing unit 104 and the lightemitting unit 107 on the basis of the photometry evaluation value.However, the photometry evaluation value may be transmitted from theimaging element 102 to the signal processing unit 104 and the lightemitting unit 107 so that the units 104 and 107 may be directlycontrolled.

As mentioned above, in the present embodiment, the apparatus isconstructed in such a manner that separately from the image pickup forlive view, the image signal of the high frame rate is generated by theimaging element and the imaging element calculates the photometryevaluation value by using the image signal. Therefore, not only the datatransfer time can be shortened but also the deterioration in imagequality in the live view can be prevented and the electric powerconsumption can be suppressed.

Third Embodiment

Subsequently, the third embodiment of the invention will be describedwith reference to FIGS. 8A to 11B.

The imaging element illustrated in FIG. 2A has an arrangementimplementation in which the first chip 20 is layered on the second chip21. In the present embodiment, an example of implementation of a signalconnection between the first chip 20 and the second chip 21 is shown.

FIGS. 8A and 8B are diagrams illustrating an example of theimplementation of the signal connection between the first chip 20 andthe second chip 21 in the imaging element according to the thirdembodiment. FIG. 8A illustrates an example in which electrodes 801 eachof which is formed with a projection on the chip 20 and electrodes 802each of which is formed with a projection on the chip 21 are directlyelectrically connected and held. FIG. 8B illustrates an example in whichelectrodes 803 and 804 formed on the chips 20 and 21 are mutuallyelectrically connected by an indirect connection device such as a wirebonding or the like and held. In any one of the above cases, the numberof signal lines connected between the chips 20 and 21 is limited to acertain extent due to a restriction of a physical arrangement of theelectrodes formed on the chips 20 and 21, or the like. A connectionresistance of each of the signal lines connected between the chips 20and 21 is relatively larger than that of signal wirings in the chips anda delicate analog signal or the like is liable to be influenced bynoises due to such a large connection resistance.

In the first and second embodiments, the construction in which the pixelsignals which are read out from the pixel portion 201 are transferred,as analog signals, from the chip 20 to the chip 21 through the columnsignal lines 202-a and 202-b. On the other hand, in the thirdembodiment, the column ADC 211 disposed on the chip 21 is shifted andarranged to the chip 20 side, and the pixel signals which aretransferred from the chip 20 to the chip 21 are replaced by the digitaloutput signal of the column ADC 211, thereby increasing noise immunity.

Subsequently, an imaging apparatus having the imaging element accordingto the present embodiment will be described. A construction of theimaging apparatus in the present embodiment is similar to that of thefirst embodiment illustrated in FIG. 1 and a construction of the imagingelement 102 differs from that of the imaging element in the firstembodiment illustrated in FIG. 2B.

FIG. 9 is a block diagram illustrating the construction of the imagingelement according to the present embodiment. In FIG. 9, substantiallythe same component elements as those in the imaging element illustratedin FIG. 2A are designated by the same reference numerals and theirdescription is omitted here.

In the imaging element 102 illustrated in FIG. 9, as a connectiondestination of the column signal lines 202-a and 202-b, the column ADC211 is disposed on the first chip 20 every column. The output signals ofthe column ADC 211 are time-sequentially read out to the horizontalsignal lines 215-a and 215-b by the column scanning circuits 213-a and213-b, respectively. The horizontal signal lines 215-a and 215-b areoutput signal lines from the chip 20. The digital pixel signals whichare read out to the horizontal signal line 215-a are sent to the signalprocessing unit 104 as output signals from the chip 20. On the otherhand, the digital pixel signals which are read out to the horizontalsignal line 215-b are sent to the switch 216 in the chip 21 as outputsignals from the chip 20. Since other component elements and theiroperations are similar to those in the case of the first embodiment,their description is omitted here.

As described above in the first embodiment, by separately performing theimage pickup for AF scanning and the image pickup for live view everyselected row, the image signals of the frame rates of the different datasizes can be obtained for the different charge accumulation times.Further, if it is intended to raise the frame rate of the image pickupfor AF scanning, it is effective that the operation conditions of thecolumn ADC 211 in the image pickup for AF scanning and those in theimage pickup for live view are set to different conditions.

FIG. 10 illustrates an example in which the operation conditions such asconversion resolving power [the number of bits], conversion gain[times], conversion time (conversion rate) [μsec], and the like areswitched for the column ADC 211 when selecting rows for live view andwhen selecting rows for AF as illustrated in FIG. 3.

In the example of FIG. 10, as compared with the image pickup for liveview, in the image pickup for AF scanning, the conversion resolvingpower is reduced from 10 bits to 8 bits and the conversion gain(input/output ratio) at the time of AD conversion is switched to a valuewhich is k times as high as that at the time of the image pickup forlive view. Unlike the image pickup for live view, according to the imagepickup for AF scanning, since an image for display is not formed, if theAF evaluation value can be merely accurately detected, it is not alwaysnecessary to certainly maintain the same level as for the conversionresolving power [the number of bits]. Rather than that, a high operationspeed owing to the reduction in conversion time is needed in many cases.

By the above construction, according to the AD conversion method, the ADoperation speed is raised and while the deterioration in sensitivity dueto the short charge accumulation time is compensated, the AD conversiontime can be shortened to the time which is k/4 times as large as that inthe image pickup for live view. The AD operation will be described indetail hereinafter.

FIGS. 11A and 11B are diagrams illustrating input/output characteristicsin the column ADC 211 when selecting the rows for live view (FIG. 11A)and when selecting the rows for AF (FIG. 11B) at this time.

Although the third embodiment is described as an implementation of thesignal connection between the first chip 20 and the second chip 21 inthe imaging element according to the first embodiment, it may be appliedto the imaging element according to the second embodiment.

Fourth Embodiment

Subsequently, a construction of an imaging apparatus having an imagingelement according to the fourth embodiment of the invention will bedescribed. Since the construction of the imaging apparatus in thepresent embodiment is similar to that of the first embodiment (FIG. 1),its description is omitted here. In the present embodiment, aconstruction of the imaging element differs from that of the imagingelement in the first embodiment.

In the third embodiment, the whole circuitry of the column ADC 211 isarranged in the chip 20 and the digital horizontal signal lines 215-aand 215-b are set to the output signal lines from the chip 20, therebyraising the noise immunity of the pixel signals. However, since a scaleof the whole circuitry of the column ADC 211 disposed every column islarge and the high operation speed is also necessary, it is not sodesirable that they are arranged in the chip 20 in which the pixelportion 201 exists. Rather than that, in a digital circuit of arelatively large scale, from a viewpoint of the high operation speed andthe low electric power consumption, it is desirable that they arearranged in the chip 21 in which narrowing of the wire width of thecircuit elements and wirings can be attained with more possibility thanthe case of the chip 20 in which the pixel portion 201 exists.Therefore, in the present embodiment, a part of the circuit block of thecolumn ADC 211 is moved into the chip 20 and the signals which aretransferred from the chip 20 to the chip 21 are converted into digitalsignals. By such a construction, while maintaining the noise immunity,an increase in circuit scale in the chip 20 can be prevented.

FIG. 12 is a diagram illustrating an internal construction of thegeneral column ADC 211. In the diagram, a reference voltage as an outputof a lump signal generator 1201 is connected to a positive input of acomparator 1204, a signal potential of the analog pixel signal isconnected to a negative input of the comparator 1204, and they arecompared and discriminated. An output of a counter 1202 for counting atime is connected to a memory 1203 for temporary storage and is held inthe memory 1203 at timing of a leading edge of a determination signalserving as an output of the comparator 1204.

FIG. 13 is a diagram for describing the AD conversion operation of thecolumn ADC 211. In the diagram, in a graph portion, an axis of abscissaindicates a time and an axis of ordinate indicates a change of an outputlevel of the lump signal generator 1201 which is input to the comparator1204 and a level of the pixel signal. A pixel signal level VS is decidedand a lump signal and the operation of the counter are started from a 0start point of the time. By holding a counter output at a cross point ofthe pixel signal level VS and the lump signal, a digital valuecorresponding to the pixel signal level, that is, an AD conversion valuecan be obtained.

The resolving power (the number of bits) at the time of the ADconversion can be set by a method whereby a time which is required untilthe lump signal reaches a full level VF (normally being positioned atneighborhood of a saturation level) of the pixel signal is adjusted byan inclination of a slope of the lump signal. For example, if theresolving power is equal to 10 bits, it is sufficient to set the slopeinto such an inclination that the time (count number) which is requireduntil the lump signal reaches the full level VF is equal to 1024 (=2¹⁰).By decreasing the inclination of the slope of the lump signal, theconversion gain can be also raised.

In the example of FIG. 13, at the time of the image pickup for live viewand at the time of the image pickup for AF scanning, the inclination ofthe slope of the lump signal is adjusted and AD conversion conditionssimilar to those shown in FIG. 10 are switched. That is, at the time ofthe image pickup for live view, the resolving power of the AD conversionis switched to 10 bits, and at the time of the image pickup for AFscanning, the resolving power is switched to 8 bits. Further, bydecreasing the inclination of the slope of the lump signal so that thelump signal is multiplied by a predetermined gain k [times], theconversion gain which is (k/4) times as large as that in the case of theimage pickup for live view is obtained and the conversion time of (k/4)times is shortened.

FIG. 14 is a block diagram illustrating the construction of the imagingelement according to the present embodiment. In FIG. 14, substantiallythe same component elements as those in the imaging element illustratedin FIG. 2A are designated by the same reference numerals and theirdescription is omitted here.

In the imaging element 102 illustrated in FIG. 14, as a connectiondestination of the column signal lines 202-a and 202-b, the comparator1204 forming a part of the circuit construction of the column ADC 211 isdisposed in the first chip 20 every column. In a manner similar to theconstruction illustrated in FIG. 12, the column ADC 211 is constructedby the lump signal generator 1201, counter 1202, memory 1203 fortemporary storage, and comparator 1204 and all of the component elementsother than the comparator 1204 are disposed in the second chip 21.

Two generators such as lump generator 1201-a for generating a referencesignal of the column signal line 202-a and lump generator 1201-b forgenerating a reference signal of the column signal line 202-b aredisposed for the lump generator 1201, and each reference signal is sentto the corresponding comparator of each column. An output of thecomparator 1204 is output every column as an output signal line from thechip 20 and is transferred to a control terminal of the correspondingmemory 1203 for temporary storage disposed on the chip 21 every column.

An output of the counter 1202 which is common to all columns is sent toa data input terminal of the memory 1203 for temporary storage. Thecounter output is held in accordance with the timing of the output ofthe comparator 1204 of each column. Data outputs of the memories 1203for temporary storage of each column are time-sequentially read out tothe horizontal signal lines 215-a and 215-b by the column scanningcircuits 213-a and 213-b. The horizontal signal lines 215-a and 215-bare output as output signal lines from the chip 20, respectively. Thedigital pixel signals which are read out to the horizontal signal line215-a are sent to the signal processing unit 104 as output signal linesfrom the chip 20. The digital pixel signals which are read out to thehorizontal signal line 215-b are sent to the switch 216 in the chip 21as output signal lines from the chip 20. Since other component elementsand their operations are substantially similar to those in the case ofthe foregoing first embodiment, their description is omitted here.

Fifth Embodiment

Subsequently, a construction of an imaging apparatus having an imagingelement according to the fifth embodiment of the invention will bedescribed. Since the construction of the imaging apparatus in thepresent embodiment is similar to that of the first embodimentillustrated in FIG. 1, its description is omitted here. In the presentembodiment, a construction of the imaging element 102 differs from thatof the imaging element in the first embodiment.

The fifth embodiment has a construction in which circuits necessary atthe time of the image pickup for AF scanning are inserted in the chip20. By this construction, such a structure that the pixel signals at thetime of the image pickup for AF scanning are output from the chip 20 isavoided, thereby reducing the number of signal lines and enabling aninfluence of noises on the pixel signals at the time of the image pickupfor AF scanning to be eliminated.

FIG. 15 is a block diagram illustrating the construction of the imagingelement according to the present embodiment. In FIG. 15, substantiallythe same component elements as those in the imaging element illustratedin FIG. 2A are designated by the same reference numerals and theirdescription is omitted here.

In FIG. 15, as a connection destination of the column signal line 202-a,a column ADC 211-a is disposed on the second chip 21 every column andthe column signal line 202-a is connected to the chip 21 as an outputsignal line from the chip 20. Output signals of the column ADC 211-a aretime-sequentially read out to the horizontal signal line 215-a by thecolumn scanning circuit 213-a. The horizontal signal line 215-a isguided to the signal processing unit 104 as an output signal line fromthe chip 21. On the other hand, as a connection destination of thecolumn signal line 202-b, a column ADC 211-b is disposed on the firstchip 20 every column. Output signals of the column ADC 211-b aretime-sequentially read out to the horizontal signal line 215-b by thecolumn scanning circuit 213-b.

The frame memory 217 and the AF evaluation value detection unit 112 arefurther disposed on the chip 20. Thus, the digital pixel signals whichare read out to the horizontal signal line 215-b are supplied to theframe memory 217 and the AF evaluation value is detected in the chip 20by the AF evaluation value detection unit 112. The detected AFevaluation value is sent to the control unit 106 as an output signalfrom the chip 20.

If the column ADC 211-b, frame memory 217, AF evaluation value detectionunit 112, and the like as circuits which are necessary at the time ofimage pickup for AF scanning are arranged in the chip 20 in which thepixel portion 201 exists, a circuit scale of the chip 20 increases. Sucha construction is not so desirable from a viewpoint of realization oflow electric power consumption. Therefore, when those circuits arearranged in the chip 20, a device to reduce the circuit electric poweris also necessary.

For this purpose, also in the present embodiment, by a method similar tothat in the third or fourth embodiment, the operation conditions areswitched for the column ADC 211-a when selecting the rows for live viewand the column ADC 211-b when selecting rows for AF, respectively. Bythis method, owing to the reduction of the conversion time in the columnADC 211-b when selecting rows for AF, the electric power of the columnADC 211-b of each column after the conversion is saved and the electricpower in the chip 20 can be reduced by an amount corresponding to thesaved power.

As for the frame memory 217, it is necessary to set the minimum memorycapacity which is limited to the evaluation area of the image pickupsignal for AF scanning. As for the AF evaluation value detection unit112 as well, it is necessary to design a logic in which the circuitscale and the electric power consumption are suppressed.

Although the invention has been described above with respect to theembodiments, the invention is not limited to those embodiments butvarious modifications within a range without departing from the essenceof the invention are also incorporated in the invention.

For example, as a control method of the functions of the foregoingembodiments, it is sufficient that the control unit controls each unitof the imaging apparatus so as to execute those functions. It is alsopossible to allow a computer provided for the imaging apparatus toexecute the programs having the functions of the foregoing embodimentsas a control program. The control program is recorded into, for example,a computer-readable storage medium. Each of the foregoing control methodand the control program has at least a control step and a displaycontrol step.

Other Embodiments

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer-executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer-executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer-executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention is described with reference to exemplaryembodiments, it is to be understood that the invention is not limited tothe disclosed exemplary embodiments. The scope of the following claimsis to be accorded the broadest interpretation so as to encompass allsuch modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2013-137064, filed on Jun. 28, 2013, which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. An imaging element having a layered structurewhich includes a first chip having a pixel portion in which pixels eachfor photoelectrically converting an optical image of an object andgenerating a pixel signal are arranged in a matrix form and a secondchip in which a drive unit of the pixel portion is arranged and having afirst output path for outputting the pixel signals of at least a firstpixel group in the pixel portion and a second output path for outputtingthe pixel signals of a second pixel group, comprising: a conversion unitconfigured to convert the pixel signals of the first output path and thesecond output path into digital signals; and a control informationgeneration unit configured to generate control information of aphotographing operation of the object by using the digital signalconverted by the conversion unit, wherein at least a part of theconversion unit is arranged in the first chip.
 2. An element accordingto claim 1, wherein the conversion unit is arranged in the first chip.3. An element according to claim 1, wherein the conversion unit includesa first conversion unit configured to convert the pixel signal of thefirst output path into the digital signal and a second conversion unitconfigured to convert the pixel signal of the second output path intothe digital signal, and a conversion condition of the first conversionunit and a conversion condition of the second conversion unit differ. 4.An element according to claim 1, wherein the control informationgeneration unit is arranged in the first chip.
 5. An element accordingto claim 1, wherein the first output path and the second output pathhave a switch unit configured to selectively output the digital signalof the first output path to the second output path.
 6. An elementaccording to claim 1, wherein the conversion unit is arranged in thefirst chip and the control information generation unit is arranged inthe second chip.
 7. An element according to claim 1, further comprisinga connection unit configured to mutually electrically connect the firstchip and the second chip, wherein the first chip is located on a lightreceiving side of the optical image.
 8. An element according to claim 1,wherein the control information generation unit generates an autofocusevaluation value, as the control information, which is used whenperforming autofocus control.
 9. An element according to claim 1,wherein the control information generation unit generates a whitebalance coefficient, as the control information, which is used whenperforming a white balance correction.
 10. An element according to claim1, wherein the conversion unit comprises a plurality of comparatorsconfigured to compare and discriminate a signal potential of the pixelsignal and a reference voltage every column arrangement of the pixelportion and output a discrimination signal, and a plurality of countersconfigured to count a time on the basis of outputs of the comparators,wherein all or at least a part of the plurality of comparators areincluded in the first chip, and wherein the plurality of counterscorresponding to the outputs of the comparators included in the firstchip are included in the second chip.
 11. An imaging apparatuscomprising: a photographing optical system for forming an optical imageof an object; the imaging element according to claim 1 for picking upthe optical image; a control unit configured to control driving of theimaging element in accordance with an image pickup mode; and a displayunit configured to display an image on the basis of the digital signalsof the first output path of the imaging element driven by the controlunit.
 12. An apparatus according to claim 11, wherein the control unitcontrols the read-out of the pixel signal from the pixel portion, readsout the pixel signals of the first pixel group to the first output pathat a first frame rate, and reads out the pixel signals of the secondpixel group to the second output path at a second frame rate lower thanthe first frame rate.
 13. An apparatus according to claim 11, whereinthe image pickup mode includes a first image pickup mode to perform theread-out of the first pixel group and a second image pickup mode toperform the read-out of the second pixel group, and in a case where thefirst image pickup mode is set, the control unit also sets the secondimage pickup mode.
 14. An apparatus according to claim 13, wherein thecontrol information generation unit generates an autofocus evaluationvalue, as the control information, which is used when performingautofocus control, and wherein in the first image pickup mode, thecontrol unit drives the photographing optical system on the basis of theautofocus evaluation value generated as the control information by thecontrol information generation unit and discriminates whether or not theautofocus evaluation value satisfies a predetermined evaluationcondition, and if it is determined that the evaluation condition issatisfied, the control unit stops the autofocus control.
 15. Anapparatus according to claim 11, further comprising a signal processingunit configured to process the digital signal of the first output path,wherein the control information generation unit generates a whitebalance coefficient, as the control information, which is used whenperforming a white balance correction, and the signal processing unitcorrects the pixel signal on the basis of the white balance coefficient.16. An apparatus according to claim 11, further comprising a lightemitting unit configured to emit light for illuminating the object,wherein the control information generation unit generates a lightemitting control amount, as the control information, for controlling alight emitting amount of the light emitting unit, and wherein thecontrol unit allows the light emitting unit to perform pre-emitting oflight, thereafter, obtains the light emitting control amount from thecontrol information generation unit, and allows the light emitting unitto perform a main light emission in accordance with the light emittingcontrol amount.
 17. An apparatus according to claim 13, wherein in theimaging element, the first output path and the second output path have aswitch unit configured to selectively output the digital signal of thefirst output path to the second output path, and the control unitcontrols a switching of the switch unit in accordance with the firstimage pickup mode and the second image pickup mode.
 18. An apparatusaccording to claim 13, wherein the control unit switches an operationcondition of the conversion unit in accordance with the first imagepickup mode and the second image pickup mode, and wherein the operationcondition includes one of a conversion rate, a conversion resolvingpower, and a conversion gain.
 19. A control method of an imagingapparatus having a photographing optical system for forming an opticalimage of an object and the imaging element according to claim 1 forpicking up the optical image, comprising: a driving step of controllinga driving of the imaging element in accordance with a first image pickupmode to read out the pixel signals of the first pixel group to the firstoutput path and a second image pickup mode to read out the pixel signalsof the second pixel group to the second output path; a display step ofdisplaying an image on the basis of the digital signal of the secondoutput path of the imaging element driven in accordance with the secondimage pickup mode; and a control step of controlling the photographingoperation in accordance with the control information generated on thebasis of the digital signal of the first output path of the imagingelement driven in accordance with the first image pickup mode.
 20. Anon-transitory computer-readable storage medium storing a program forcausing a computer to execute the control method according to claim 19.